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Background : Plasmacytoma is a neoplasm originating in plasma cells, derived from B lymphocytes. Extramedullary presentation is the most common form of plasmacytoma, mainly in the skin and rarely in other tissues, including the vertebral canal. Extramedullary plasmacytoma (EMP) occurs more frequently in senile dogs and rarely in cats and some dog breeds have predisposition for this type of neoplasm. The aim of this study was to report plasmacytoma in a dog located adjacent to the thoracic vertebrae. Case : An approximately 5-year-old mongrel male with sudden paraplegia resulting from upper motor neuron injury was admitted to a University Hospital. The dog presented a six-centimeter diameter mass in the dorsal region, adjacent to the thoracic vertebrae. The leucogram presented mild leukopenia by eosinopenia and lymphopenia. Myelogram associated with epidurography showed a fill failure in the contrast column between the seventh and ninth thoracic vertebrae, and there were no osteolysis points in the thoracic vertebrae, adjacent to the neoplastic mass. The evaluation of the intervertebral spaces between the fourth to ninth thoracic vertebrae presented no increase in radiopacity, nor alterations in the size of intervertebral spaces, indicating intervertebral disc extrusion. The laterolateral radiographs showed an alignment of the vertebrae and vertebral canal, without presence of bone neoformations on the ventral face of the vertebral bodies. The animal was euthanized and fragments of mass were collected for histological analysis. Macroscopic findings presented a non-encapsulated well-delimited mass, with color ranging from white to reddish. Microscopically, there was proliferation of moderately differentiated round cells in bone and muscle tissues, arranged in mantle, with moderately eosinophilic cytoplasm, and rounded nucleus with eccentric location, coarse chromatin sometimes indistinct. These cells presented moderate anisocytosis and, in general, one mitosis per field. Intradural extramedullary plasmacytoma was diagnosed. Discussion : The present report presented a diagnosis of intradural EMP, generating compression of the spinal cord because of its invasive growth, reaching the canal and, thus, reducing its lumen. The clinical status of the dog was compatible with thoracolumbar lesion of upper motor neuron, which causes paresis and ataxia in pelvic limbs. In this case, it was not possible to establish early diagnosis because the dog had been rescued from the streets recently. Radiographic examination was important to identify the real size of the mass, and the myelography confirmed spinal cord compression. The definitive diagnosis was obtained by histological examination. Although extramedullary plasmacytoma is a low-frequency neoplasm, in the present report, its manifestation was atypical, more aggressive, invading the medullary canal and compressing the spinal cord. Spinal cord compression may lead to degeneration of axons because of alterations in the vascular permeability associated with local inflammatory process, reducing the oxygen supply to nervous tissues, resulting in cellular degeneration. The occurrence of atypical neoplastic growth should be included as a differential diagnosis for lesions in upper motor neuron in cases of spinal cord compression. This is an atypical location for this kind of neoplasia, and cases of medullary compression of neoplastic masses should be included as a differential diagnosis.

Background: Pneumomediastinum is a rare entity characterized by the introduction of air into the mediastinum. Primary or spontaneous pneumomediastinum may occur in the absence of any disease whereas secondary pneumomediastinum may be due to a number of precipitating factors. The clinical picture is severe and the onset is acute. The present report describes the clinical presentation, treatment, and the findings of a forensic investigation of a case of generalized subcutaneous emphysema secundary to pneumomediastinum in a newborn kitten. Case: A newborn kitten was presented to a veterinary climic with a history of generalized air accumulation in the subcutaneous tissue of acute onset which was noted whenever the animal suckled. Clinical care and radiographic examination were performed. Radiographic findings included areas of radiolucency within the subcutis suggestive of generalized subcutaneous emphysema. In the thoracic cavity, there was ventral displacement of the thoracic trachea and increased radiolucency in the cranial mediastinum suggestive of pneumomediastinum. There was loss of definition of the cervical trachea suggestive of tracheal rupture. Based on the radiographic findings, the clinician decided to aspirate the air accumated within the subcutis using a needle and a syringe. However, this emphysema rapidly formed after the subcutaneous air was aspirated. Euthanasia was elected due to the poor prognosis and the animal was submitted for necropsy. Main gross findings included traumatic intercostal laceration adjacent to the lungs under the axilla and tracheal perforation. Tracheal perforation resulted in persistent air leakage from the trachea causing pneumomediastinum which evolved into generalized subcutaneous emphysema causing the animal to inflate as air became trapped within the subcutis imparting a blown up appearance to the cat. Microscopically pulmonary collapse was observed. Symptomatic treatment was instituted and consisted of puncturing the distended skin with needle and syringe. Percutaneous drainage of the subcutaneous air was unsuccessful.Discussion: In the present case, the diagnosis of generalized subcutaneous emphysema due to pneumomediastinum in a newborn kitten was based on the history, clinical signs, radiographic findings, and gross necropsy lesions. However, the histopathological findings were non-specific. The present case is an example of secondary pneumomediastinum. Tracheal perforation resulted in massive air penetration into the mediastinum. Generalized subcutaneous emphysema developed as a complication of the pneumomediastinum. Queens carry their offspring using their mouth. We suggest that the tracheal lesion is a penetrating tracheal trauma and that this injury was inflicted by the mother's canine teeth as she transported the kitten with the animal's neck and chest inside her mouth. There was no history that the kitten was attacked by other animal or of any other type of trauma. Initial conservative treatment consisted of puncturing the skin in order to release subcutaneous air and relieve pain. Oxygen supply was not considered due to practical reasons since such supportive therapy would worsen the clinical picture of the patient. Necropsy findings were of major importance to establish a definitive diagnosis. Gross lesions included tracheal perforation, which caused pneumomediastinum through air leakage into the mediastinum and lead to the subcutaneous emphysema. We conclude that unintentional traumatic injuries in a newborn kitten caused by the queen should be considered as a cause of pneumomediastinum and subcutaneous emphysema. The clinical picture is severe, of acute onset, and exhibits a rapidly progressive course.